I'm going to begin by echoing Raj B. here: I'm roughly 70 pages into this 300+-page PDF and I'm so sick of the phrase "see Barrowmaze Complete" that I could scream. Even an entry in the back that says something like "Funeral Pyre Zombies -- see Barrowskin Complete or reskin Fire Snake from MMp265" would be an improvement. This was sold as a standalone product, not as a Barrowmaze supplement.
The maps are great, there are some good ideas (if not as fleshed out as I'd like), the writing is mostly clear. I'd like to see this designed better for use at the table-- inline stat blocks would be handy to avoid flipping back and forth and back and forth. Also, there's a tendency to give information a little late. Room 42 of one area says "A detachment of [enemies] normally guard this chamber (85%). If not, they may be training in #27-28." Think that might be worth mentioning a little earlier, say in #27 or #28? Me too.
If you're planning to buy one Greg Gillespie megadungeon, don't get this one. Buy Barrowmaze instead. It's not perfect, but it's good, much better than this.
If the publisher were to go through and make the other monster stats available as a free PDF or something, I'd probably rate this as 4 stars. As it is, I'll steal a few ideas/mechanics from this but I have no desire to run it for my players. When I'm paying $30ish for an adventure module, I expect that I'm paying for someone else to have done most of the work for me. That wasn't the case here.